Connecting across the two major bones of the navicular and the calcaneus and running under the talus is the spring ligament, a strong band-like structure which braces the foot arch. The weight of the body presses down to flatten the arch and the spring ligament holds between the two bones, becoming tauter as more weight is applied. Due to its great strength the spring ligament is adapted to manage the high forces generated by activities such as running, hopping or jumping, which are too vigorous for the musculature to able to hold the arch in place. The muscles contribute to arch maintenance but at a longer term lower level.
The ankle has accessory movements like all our other synovial joints. These are small internal gliding and sliding movements which naturally occur within a joint during normal movement but cannot be independently performed. Accessory movements are vital to the normal functioning of joints and if they are limited or lost then the joint loses some of its functional ability also. As the weight passes onto the foot the forefoot and toes are flat on the ground the talus is forced inwards to a small degree by the downwards forces.
This tensions the foot by twisting it slightly and along with the stretching of the longitudinal ligaments by the arch being flattened this gives the foot some elastic recoil when the weight begins to be removed from the foot. This gives a little kick of propulsion as we step forwards, perhaps being what we refer to as a spring in the step. As the foot encounters the unstable surface of rough ground it must accommodate to the differing levels and the joint between the talus and the calcaneum, the subtalar joint, is important in this adjustment.
The sideways movements of the subtalar joint allow the heel to move inwards and outwards whilst the talus is still held securely in the ankle mortise, with much more inward movement of the heel bone than outward. There are various ways in which we can walk, in our foot posture, which can compromise the function of the foot and lead to painful foot problems. If the hips and feet are turned out as we walk this tends to make the outer border of the foot hit the ground first, meaning the foot has to roll inwards to hit the ground itself.
As the foot rolls in this amount the arch tends to flatten, stretching the sling of supporting muscle tendons from the tibialis posterior and tibialis anterior muscles of the calf. This allows the talus to slip from its top position in the foot arch to some degree. As the forces involved in this medial rolling of the arch are very great this gradually over time makes the foot become abnormal when it performs like a static platform rather than a springy, dynamic part.
There is a greater range of movement in a medial (inwards) direction in the foot than in the lateral (outwards) direction which is limited by the fibula which gets in the way. This increases the likelihood of any sideways stresses resulting in a rapid inwards movement of the foot, causing an ankle sprain. Flat feet are often not painful in themselves but their abnormal position has knock on effects for all the joints above them including the ankle, knee, hips and low back. The forefoot also has a sideways arch even though this is small compared to the main foot arch, but if it flattens it places abnormal stresses on the head of the second metatarsal.
The lateral ligaments of the foot are the ones typically sprained due to the tendency of the ankle to go over as the foot moves forcibly inwards. The subtalar joint is always involved and damaged when there is a significant sprain of the ankle joint and this can cause instability of this area and lead to repetitive ankle sprains. Multiple sprains make the local tissues swell and this with time thickens up, turning into scar and giving problems if the ankle has been held still for some weeks in a cast, reducing both the stability and mobility of the area. - 14130
The ankle has accessory movements like all our other synovial joints. These are small internal gliding and sliding movements which naturally occur within a joint during normal movement but cannot be independently performed. Accessory movements are vital to the normal functioning of joints and if they are limited or lost then the joint loses some of its functional ability also. As the weight passes onto the foot the forefoot and toes are flat on the ground the talus is forced inwards to a small degree by the downwards forces.
This tensions the foot by twisting it slightly and along with the stretching of the longitudinal ligaments by the arch being flattened this gives the foot some elastic recoil when the weight begins to be removed from the foot. This gives a little kick of propulsion as we step forwards, perhaps being what we refer to as a spring in the step. As the foot encounters the unstable surface of rough ground it must accommodate to the differing levels and the joint between the talus and the calcaneum, the subtalar joint, is important in this adjustment.
The sideways movements of the subtalar joint allow the heel to move inwards and outwards whilst the talus is still held securely in the ankle mortise, with much more inward movement of the heel bone than outward. There are various ways in which we can walk, in our foot posture, which can compromise the function of the foot and lead to painful foot problems. If the hips and feet are turned out as we walk this tends to make the outer border of the foot hit the ground first, meaning the foot has to roll inwards to hit the ground itself.
As the foot rolls in this amount the arch tends to flatten, stretching the sling of supporting muscle tendons from the tibialis posterior and tibialis anterior muscles of the calf. This allows the talus to slip from its top position in the foot arch to some degree. As the forces involved in this medial rolling of the arch are very great this gradually over time makes the foot become abnormal when it performs like a static platform rather than a springy, dynamic part.
There is a greater range of movement in a medial (inwards) direction in the foot than in the lateral (outwards) direction which is limited by the fibula which gets in the way. This increases the likelihood of any sideways stresses resulting in a rapid inwards movement of the foot, causing an ankle sprain. Flat feet are often not painful in themselves but their abnormal position has knock on effects for all the joints above them including the ankle, knee, hips and low back. The forefoot also has a sideways arch even though this is small compared to the main foot arch, but if it flattens it places abnormal stresses on the head of the second metatarsal.
The lateral ligaments of the foot are the ones typically sprained due to the tendency of the ankle to go over as the foot moves forcibly inwards. The subtalar joint is always involved and damaged when there is a significant sprain of the ankle joint and this can cause instability of this area and lead to repetitive ankle sprains. Multiple sprains make the local tissues swell and this with time thickens up, turning into scar and giving problems if the ankle has been held still for some weeks in a cast, reducing both the stability and mobility of the area. - 14130
About the Author:
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapists, physiotherapy, Physiotherapists in Exeter, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
No comments:
Post a Comment